Bookworm,
having used clock-map-ground extensively, very low level in a tactical environment with lots of other distractions and much later than the 70's or 80's I have to disagree with you.
If VFR, proper use of this technique works. GPS is good and cannot be dismissed. However reliance on GPS without proper training in navigational techniques is a folly. We've all read stories of people who have driven into rivers etc because they blindly follow SATNAV - a lot of today's drivers can barely read a map.
People with minimal hours under their belt with a PPL are in danger of going down the same route.
I'm not against GPS and the 1000 hours quote was a bit tongue in cheek - however I'm with DFC in believing that proper nav training should be done, similarly when doing IMC ratings, upon completion reliance on GPS IFR is again, not a sound attitude.
Maintaining the 'basic' skills and using both this and GPS to cross check each other is the only sensible way to navigate, if one insists on having GPS.
And by cross checking I don't mean carry two GPS units!!